The present invention relates to an X-ray analyzer and a spectrum generation method.
Methods of performing an elemental analysis of a specimen by irradiating the specimen with primary rays such as electron beams or X-rays and detecting X-rays generated from the specimen are known.
An example of such methods is energy-dispersive X-ray spectroscopy which involves irradiating a specimen with electron beams in an electron microscope and detecting X-rays generated from the specimen to measure a composition of the specimen. Energy-dispersive X-ray spectroscopy takes advantage of the fact that a characteristic X-ray has energy unique to elements constituting a specimen. In a spectrum of a characteristic X-ray obtained by energy-dispersive X-ray spectroscopy, an elemental species contained in a specimen is obtained from an energy value of a peak of the spectrum and a content of the elemental species is obtained from an area of the peak of the spectrum.
In addition, X-ray detection systems using a diffraction grating and a charge-coupled device (CCD) image sensor are known as another example of the methods described above. For example, with an X-ray detection system disclosed in JP-A-2012-58146, a specimen is irradiated with electron beams, X-rays (soft X-rays) generated from the specimen are collected by a mirror and dispersed by a diffraction grating, and dispersed X-rays (soft X-rays) are received by an X-ray CCD image sensor to acquire a spectrum.
With a detection device using a CCD image sensor, since the CCD image sensor is cooled, hydrocarbon or the like is deposited on a surface of the CCD image sensor and causes sensitivity of the CCD image sensor to decline.
For example, creating an ultra-high vacuum in a specimen chamber in which a detector is disposed enables a decline in the sensitivity of the detector due to such contamination to be suppressed. However, realizing an ultra-high vacuum is cost-intensive despite its limited effectiveness. Therefore, a technique capable of reducing an effect of a decline in sensitivity of a detector due to contamination by a simpler method is required.